WO2015163351A1

WO2015163351A1 - Pneumatic tire manufacturing method and manufacturing apparatus

Info

Publication number: WO2015163351A1
Application number: PCT/JP2015/062203
Authority: WO
Inventors: 智行酒井
Original assignee: 横浜ゴム株式会社
Priority date: 2014-04-23
Filing date: 2015-04-22
Publication date: 2015-10-29
Also published as: US20170050399A1; EP3135469A4; EP3135469A1; CN106163783A

Abstract

　Provided are a manufacturing method and a manufacturing apparatus for a pneumatic tire, with which a tread portion can be formed with good dimensional accuracy, while minimizing thermal degradation of the base tire. A rigid inner mold (2) made from metal is abutted against the tire inner surface in an area corresponding to the tread portion (TR) of the base tire (BT), and in this state, the base tire (BT) is supported from the inner side by the tough, rigid inner mold (2). In this state, unvulcanized rubber (R) is injected into the cavity (11) of a tread mold (10) that covers the base tire (BT) outside peripheral surface corresponding to the tread portion (TR), and the unvulcanized rubber (R) is vulcanized to form the tread portion (TR) on the outside peripheral surface of the base tire (BT), as well as to unify the tread portion (TR) with the outside peripheral surface.

Description

Pneumatic tire manufacturing method and manufacturing apparatus

The present invention relates to a method and apparatus for manufacturing a pneumatic tire, and more particularly, to a method and apparatus for manufacturing a pneumatic tire capable of forming a tread portion with high dimensional accuracy while suppressing thermal deterioration of a base tire. Is.

Various so-called retreaded tire manufacturing methods have been proposed in which a new tread portion is formed on a base tire obtained by cutting the rubber of a tread portion of an existing pneumatic tire (see, for example, Patent Document 1). In the method proposed in Patent Document 1, an existing manufacturing facility is used, and an internal pressure is applied in a state where a vulcanization bladder disposed inside a base tire is inflated. In this state, unvulcanized rubber is injected into a space formed between a tire mold disposed on the outer side in the circumferential direction of the base tire and the outer surface in the circumferential direction of the base tire. The injected unvulcanized rubber is vulcanized to form a tread portion and to be integrated with the outer circumferential surface of the base tire.

In this method, since the thermal fluid is supplied to the vulcanizing bladder and expanded, the base tire is heated from the inside. In other words, the vulcanized rubber forming the base tire is heated by the vulcanization bladder from the inside of the tire, so that there is a problem that it is thermally deteriorated.

Also, the injection pressure of the unvulcanized rubber to be injected is generally significantly higher than the internal pressure (about several MPa) of the expanding vulcanized bladder. Therefore, even if the inside of the base tire is pressed by the expanded vulcanized bladder, the base tire is deformed so as to be recessed inward by the injection pressure of the unvulcanized rubber. Due to the influence of this deformation, there is a problem that the dimensional accuracy of the formed tread portion is lowered. In the cited document 1, the pressure P1 of the unvulcanized rubber in the tread molding space is set slightly higher than the internal pressure P2 applied to the base tire (see paragraph 0040). That is, in the invention described in the cited document 1, since the injection pressure of the unvulcanized rubber cannot be set high, there are a disadvantage that the injection time becomes long and a disadvantage that it is difficult to sufficiently spread the unvulcanized rubber in the tread molding space. Arise.

Japanese Unexamined Patent Publication No. 2011-31452

The object of the present invention relates to a pneumatic tire manufacturing method and manufacturing apparatus, and more specifically, a pneumatic tire manufacturing method and a manufacturing method capable of forming a tread portion with high dimensional accuracy while suppressing thermal deterioration of a base tire. To provide an apparatus.

In order to achieve the above object, the pneumatic tire manufacturing method of the present invention has a metal rigid inner mold that can be expanded and contracted arranged inside a base tire, and is within the range of the tire inner surface corresponding to the tread portion of the base tire. With the rigid inner mold in contact, the outer peripheral surface of the base tire corresponding to the tread portion is covered with a tread mold, and then unvulcanized rubber is injected into the cavity of the tread mold, By vulcanizing the unvulcanized rubber, a tread portion is formed on the outer peripheral surface of the base tire, and the tread portion is integrated with the outer peripheral surface.

Another method of manufacturing a pneumatic tire according to the present invention is such that a cylindrical metal rigid inner mold that can be divided into a plurality of parts in the circumferential direction is arranged inside a base tire, and the tire inner surface corresponding to the tread portion of the base tire The rigid inner mold is brought into contact with the above range, the base tire is disposed in a vulcanizing mold together with the rigid inner mold, and the outer peripheral surface of the base tire corresponding to the tread portion is Cover with a vulcanizing mold, and then inject unvulcanized rubber into a cavity formed between the inner peripheral surface of the vulcanizing mold and the outer peripheral surface of the base tire, and this unvulcanized rubber. To form a tread portion on the outer peripheral surface of the base tire and to integrate the tread portion with the outer peripheral surface to manufacture a pneumatic tire, and to connect the pneumatic tire to the inner side of the pneumatic tire. Together with the rigid inner mold placed in Extraction out of the serial vulcanizing mold, characterized in that removing the rigid inner mold in the outer of said vulcanizing mold from the inside of the pneumatic tire.

The pneumatic tire manufacturing apparatus according to the present invention includes an expandable / reducible metal rigid inner mold disposed inside a base tire, and a tread metal disposed so as to cover the outer peripheral surface of the base tire corresponding to the tread portion. A mold and an injection machine that injects unvulcanized rubber into the cavity of the tread mold, and the rigid inner mold is brought into contact with the inner surface of the tire corresponding to the tread portion of the base tire. The unvulcanized rubber is injected.

Another pneumatic tire manufacturing apparatus according to the present invention includes a cylindrical metal rigid inner mold that can be divided into a plurality of pieces in a circumferential direction, which is disposed inside the base tire, and the base tire including the rigid inner mold. And a cavity formed between the inner peripheral surface of the vulcanization mold and the outer peripheral surface of the base tire, and a vulcanizing mold that covers the outer peripheral surface of the base tire corresponding to the tread portion. An injection machine for injecting unvulcanized rubber, and injecting the unvulcanized rubber into the cavity in a state where the rigid inner mold is in contact with the inner surface of the tire corresponding to the tread portion of the base tire Thus, after the tread portion formed by vulcanizing the unvulcanized rubber is integrated with the outer peripheral surface of the base tire to manufacture a pneumatic tire, the rigidity disposed inside the pneumatic tire is set. The inner mold is the manufactured pneumatic tie. Wherein is taken out of the vulcanizing mold together, characterized in that the structure to be removed from the inside of the pneumatic tire in the outer of said vulcanizing mold.

According to the former method and apparatus for manufacturing a pneumatic tire of the present invention, the base tire is fastened from the inside with the metal rigid inner mold in contact with the inner surface of the tire corresponding to the tread portion of the base tire. It is supported by a rigid inner mold. In this state, unvulcanized rubber is injected into the cavity of the tread mold that covers the outer peripheral surface of the base tire corresponding to the tread portion, so that the problem of the base tire being recessed inside due to the injection pressure of the unvulcanized rubber is avoided. it can. Further, since the rigid inner mold that is in contact with the tire inner surface of the base tire is made of metal, it functions as a cooling fin that releases the heat of the base tire. Therefore, the temperature rise of the base tire injected with the unvulcanized rubber can be suppressed, which is advantageous for suppressing the thermal deterioration of the base tire.

Since the base tire is supported from the inside by a rigid inner mold, it becomes possible to set the injection pressure of unvulcanized rubber high, and this has the advantage that the injection time can be shortened. There is also an advantage that it is easy to spread. These advantages are also advantageous for improving dimensional accuracy.

In the former method and apparatus for producing a pneumatic tire according to the present invention, the rigid inner mold is constituted by a plurality of segments divided in the circumferential direction, and these segments are arranged at positions where the diameters have been expanded, so that the tread portion of the base tire is provided. It can also be made to contact the range of the tire inner surface corresponding to. Thereby, it is easy to arrange the rigid inner mold inside the base tire, and it is easy to take out the rigid inner mold outside the manufactured pneumatic tire.

According to the latter method and apparatus for manufacturing a pneumatic tire of the present invention, the base tire is fastened from the inside with the metal rigid inner mold in contact with the inner surface of the tire corresponding to the tread portion of the base tire. It is supported by a rigid inner mold. In this state, unvulcanized rubber is injected into the cavity formed between the inner peripheral surface of the vulcanizing mold that covers the outer peripheral surface of the base tire corresponding to the tread portion and the outer peripheral surface of the base tire. It is possible to avoid the problem that the tire is recessed inward due to the injection pressure of the vulcanized rubber. Further, since the rigid inner mold that is in contact with the tire inner surface of the base tire is made of metal, it functions as a cooling fin that releases the heat of the base tire. Therefore, the temperature rise of the base tire injected with the unvulcanized rubber can be suppressed, which is advantageous for suppressing the thermal deterioration of the base tire.

Furthermore, the operation of placing the rigid inner mold inside the base tire and the operation of removing the rigid inner mold from the inside of the manufactured pneumatic tire can be performed outside the vulcanization mold. Therefore, it is not necessary to provide a mechanism for performing these operations in the manufacturing apparatus, which is advantageous for simplifying the manufacturing apparatus.

In the latter method and apparatus for producing a pneumatic tire according to the present invention, when the base tire is placed in the vulcanizing mold together with the rigid inner mold, the injected unvulcanized rubber is injected into the plan of the injection machine. It is also possible to fill the cylinder in which the jar is installed. This makes it possible to quickly inject unvulcanized rubber into the cavity, making it difficult for the unvulcanized rubber to receive an unnecessary heat history.

In the former and latter pneumatic tire manufacturing methods of the present invention, the unvulcanized rubber can be injected and vulcanized while cooling the inside of the base tire through the rigid inner mold. In the former and the latter pneumatic tire manufacturing apparatuses of the present invention, a cooling means for cooling the rigid inner mold may be provided. Thereby, since the temperature rise of a base tire can be suppressed positively, it becomes more and more advantageous in suppressing the thermal deterioration of a base tire.

As the base tire, for example, a tire formed by cutting rubber on a tread portion of an existing pneumatic tire is used. As the unvulcanized rubber, a studless tire can be manufactured using a rubber compound for a studless tire. The existing pneumatic tire is a studless tire, and a rubber compound of a type different from the rubber compound used in the tread portion of the existing studless tire can be used as the unvulcanized rubber. The rubber compound used in the tread portion of the existing studless tire and the rubber compound of the tread portion formed on the outer peripheral surface of the base tire have at least one characteristic of hardness, specific gravity, and friction characteristics under the same conditions. It can be different.

FIG. 1 is an overall schematic diagram illustrating a pneumatic tire manufacturing apparatus according to the present invention, partially in a sectional view. FIG. 2 is an explanatory view illustrating the rigid inner mold and the tread mold of FIG. 1 in plan view. FIG. 3 is an explanatory view illustrating the rigid inner mold of FIG. 2 in plan view. FIG. 4 is an explanatory view illustrating the rigid inner mold in a state in which the short segment is moved to the reduced diameter position in plan view. FIG. 5 is an explanatory diagram illustrating, in plan view, a rigid inner mold in which a long segment is also moved to a reduced diameter position and reduced in diameter. FIG. 6 is an explanatory view showing a modification of the segment in cross-sectional view. FIG. 7 is an explanatory view illustrating a state in which unvulcanized rubber is injected into the cavity of FIG. 1 in a cross-sectional view. FIG. 8 is an explanatory view illustrating another rigid inner mold in plan view. 9 is a cross-sectional view taken along the line AA in FIG. FIG. 10 is a left half vertical cross-sectional view illustrating the step of removing the rigid inner mold from the manufactured pneumatic tire. FIG. 11 is a left half longitudinal sectional view of a rigid inner mold illustrating the next step of FIG. FIG. 12 is an overall schematic diagram illustrating a part of another embodiment of the pneumatic tire manufacturing apparatus of the present invention in a tire width direction sectional view. FIG. 13 is an explanatory view illustrating the manufacturing apparatus of FIG. 12 in plan view. FIG. 14 is an explanatory view illustrating the rigid inner mold of FIG. 13 in plan view. FIG. 15 is an explanatory view illustrating a state where the rigid inner mold of FIG. 14 is separated and divided in a plan view. FIG. 16 is an explanatory view illustrating the state in which unvulcanized rubber is injected into the cavity of FIG. 12 in a tire width direction sectional view. FIG. 17 is an explanatory view illustrating the step of arranging another rigid inner mold inside the base tire in a sectional view in the tire width direction. FIG. 18 is an explanatory view illustrating the state in which the rigid inner mold of FIG. 17 is disposed inside the base tire in a tire width direction sectional view. FIG. 19 is an explanatory view illustrating a base tire in which the rigid inner mold of FIG. FIG. 20 is an explanatory view illustrating a step of arranging another rigid inner mold inside the base tire in a tire width direction sectional view. FIG. 21 is an explanatory view illustrating the step of FIG. 20 in a tire side view. FIG. 22 is an explanatory view illustrating a state in which the rigid inner mold of FIG. 20 is arranged inside the base tire in a tire width direction sectional view.

Hereinafter, a method for producing a pneumatic tire and a vulcanizing apparatus of the present invention will be described based on the embodiments shown in the drawings.

The pneumatic tire manufacturing apparatus 1 of the present invention illustrated in FIGS. 1 to 3 includes a base metal BT 2 corresponding to a tread portion TR, and a rigid inner mold 2 that can be expanded and contracted, which is disposed inside the base tire BT. A tread mold 10 disposed so as to cover the outer peripheral surface of the tread mold, and an injection machine 13 for injecting the unvulcanized rubber R into the cavity 11 of the tread mold 10. The manufacturing apparatus 1 of this embodiment further includes cooling means 8 and 9 for cooling the rigid inner mold 2.

The base tire BT refers to a tire without a tread portion TR in a normal pneumatic tire. The base tire BT is formed by cutting rubber of a tread portion TR of an existing pneumatic tire that has been used. The surface is buffed after rubber cutting. Alternatively, in a normal pneumatic tire manufacturing process, only the tread portion TR can be omitted for manufacturing. That is, a new base tire BT that is not used can be manufactured. The present invention can use a base tire BT and a new base tire BT formed by cutting rubber of a tread portion TR of an existing pneumatic tire.

The rigid inner mold 2 is composed of a plurality of segments 3 (3A, 3B) divided in the circumferential direction. Examples of the material of the rigid inner mold 2 include metals such as carbon steel, aluminum, and aluminum alloys. In this embodiment, there are two types of four long segments 3A having a relatively large circumferential length and four short segments 3B having a relatively small circumferential length. Both end surfaces of the short segment in the circumferential direction are parallel to the expansion / contraction direction. The long segments 3A and the short segments 3B are alternately arranged in the circumferential direction. Each

segment

3A, 3B is attached to a cylinder 5a extending radially from the central axis 5.

The segment 3 (3A, 3B) arranged annularly around the central axis 5 moves the short segment 3B radially inward (reduced diameter position) by retracting the rod of the cylinder 5a as illustrated in FIG. Then, as shown in FIG. 5, the rigid inner mold 2 is reduced in diameter by retracting the rod of the cylinder 5a and moving the long segment 3A inward in the radial direction (diameter reduction position). For example, the short segment 3B is moved to the reduced diameter position and then removed from the cylinder 5a, and then the long segment 3A is moved to the reduced diameter position.

In the reduced-diameter rigid inner mold 2, the rod of the cylinder 5a is moved forward to move the long segment 3A to the outside in the radial direction (expanded position), and then the rod of the cylinder 5a is moved forward to move the short segment 3B to the radial direction. The diameter is expanded by moving to the outside (diameter expansion position). In the rigid inner mold 2 with the expanded diameter, the outer surfaces of the

segments

3A and 3B are continuously annularly abutted on the range of the tire inner surface corresponding to the tread portion TR of the base tire BT.

All the short segments 3B can be moved simultaneously or separately. Each of the long segments 3A can be moved simultaneously or separately.

The width dimension (the vertical dimension in FIG. 1) of each

segment

3A, 3B is set slightly smaller than the interval between the bead portions Tb facing the base tire BT. Therefore, each

segment

3A, 3B can be smoothly expanded and contracted by passing between the pair of bead portions Tb.

As illustrated in FIG. 6, auxiliary plates 3 a can be rotatably provided at both ends of the segment 3. In this segment 3, the auxiliary plate 3a is expanded and contracted between the pair of bead portions Tb in a state in which the auxiliary plate 3a is folded (a state in which the auxiliary plate 3a is not substantially projected vertically). After the segment 3 moves from the inner side in the radial direction to the outer side and passes between the pair of bead portions Tb, the auxiliary plate 3a is developed and brought into contact with the tire inner surface of the base tire BT. The auxiliary plate 3a is locked at the deployed position and maintains the developed state. Thereby, a much wider range of the tire inner surface can be supported by the rigid inner mold 2.

The cooling means is composed of, for example, a cooler 9 and a cooling path 8. The cooling path 8 is provided in the rigid inner mold 2 (segment 3). The cooler 9 supplies a cooling medium such as water to the cooling path 8. By this cooling means, the temperature of the rigid inner mold 2 (segment 3) is maintained at 40 ° C. or higher and 120 ° C. or lower, for example.

The tread mold 10 is composed of a plurality of divided molds 10a divided in the circumferential direction. In this embodiment, four divided molds 10a are assembled in a ring shape. Each split mold 10 a is formed with a cavity 11 and an injection path 12 connected to the cavity 11. The surface of the cavity 11 has a shape that forms a tread pattern of the pneumatic tire T to be manufactured. One end of the injection path 12 is connected to the injection port of the injection machine 13.

The other end of the injection path 12 is connected to the position of the cavity 11 corresponding to, for example, a tread land portion or a circumferential groove of the pneumatic tire T to be manufactured. The injection path 12 is preferably branched into a plurality of paths on the way and connected to the cavity 11.

A heating path 14 connected to the heater 15 is further formed in each split mold 10a. The heater 15 supplies a heating medium such as steam, and the supplied heating medium flows through the heating path 14 to heat the split mold 10a.

The injection machine 13 includes a cylinder 13a that accommodates the unvulcanized rubber R while being heated at a predetermined temperature, and a plunger 13b that extrudes the unvulcanized rubber R that is accommodated in the cylinder 13a. The unvulcanized rubber R is injected at a predetermined injection pressure by moving the plunger 13b forward. This injection pressure is, for example, 10 MPa or more and 50 MPa or less.

The unvulcanized rubber R has flow characteristics that can be injected and may be any specification that can be vulcanized. For example, natural rubber, diene rubbers such as IR, SBR, BR, butyl rubber, halogenated butyl rubber, EPDM, etc. Various compounding materials such as non-diene rubber, carbon black, oil, anti-aging agent, processing aid, softener, plasticizer, vulcanizing agent, vulcanization accelerator and vulcanization retarder are appropriately blended.

An example of the procedure of the method for manufacturing a pneumatic tire according to the present invention using the manufacturing apparatus 1 will be described.

The long segment 3A and the short segment 3B are sequentially moved to the enlarged diameter position and inserted inside the base tire BT. After the insertion, as shown in FIG. 3, the rigid inner mold 2 is locked in the expanded state to maintain the expanded state. In the rigid inner mold 2 whose diameter has been expanded, each segment 3 is in contact with the range of the tire inner surface corresponding to the tread portion TR of the base tire BT. That is, the tire inner surface corresponding to the tread portion TR of the base tire BT is firmly supported by the segments 3 arranged in an annular shape.

A tread mold 10 (divided mold 10a) is arranged on the outer peripheral side of the base tire BT, and the outer peripheral surface of the base tire BT corresponding to the tread portion TR is covered with the tread mold 10. As a result, the cavity 11 of the tread mold 10 is closed by the outer peripheral surface of the base tire BT to form a closed space.

Next, as illustrated in FIG. 7, the unvulcanized rubber R is injected from the injection machine 13 into the cavity 11 of the tread mold 10, and the cavity 11 is filled with the unvulcanized rubber R through the injection path 12. The unvulcanized rubber R filled in the cavity 11 is formed into a predetermined shape by the cavity 11. Then, the unvulcanized rubber R is vulcanized while the tread mold 10 is heated by the heating medium flowing through the heating path 14. When the unvulcanized rubber R is vulcanized, a tread portion TR made of the vulcanized rubber is formed on the outer peripheral surface of the base tire BT, and this tread portion TR is vulcanized and bonded to the outer peripheral surface of the base tire BT. And unite. Thereby, the pneumatic tire T is completed.

Then, the rigid inner mold 2 whose diameter has been expanded is reduced in diameter, and is taken out from the inside to the outside of the base tire BT (manufactured pneumatic tire T).

As described above, in the present invention, the base tire BT is supported from the inside by the solid rigid inner mold 2 in a state where the metal rigid inner mold 2 is in contact with the inner surface of the tire. Since the unvulcanized rubber R is injected into the cavity 11 of the tread mold 10 in this state, it is possible to avoid the problem that the base tire BT is recessed inward due to the injection pressure of the unvulcanized rubber R.

In addition, since the rigid inner mold 2 in contact with the tire inner surface of the base tire BT is made of metal, it functions as an air-cooled cooling fin that releases heat from the base tire BT. Therefore, the temperature rise of the base tire BT can be suppressed, which is advantageous for suppressing thermal deterioration of the vulcanized rubber forming the base tire BT.

In this embodiment, the unvulcanized rubber R can be injected and vulcanized while cooling the inside of the base tire BT through the rigid inner mold 2 by the cooling means 8 and 9. Therefore, since the temperature rise of the base tire BT can be positively suppressed, it becomes more and more advantageous for suppressing thermal deterioration of the base tire BT.

Since the base tire BT is supported by the rigid inner mold 2 from the inside, the injection pressure of the unvulcanized rubber R can be set higher than when the inside of the base tire BT is supported by the vulcanizing bladder. Along with this, there is an advantage that the injection time can be shortened, which contributes to improvement of tire productivity. Further, there is an advantage that the unvulcanized rubber R can be easily spread over the entire range of the cavity 11. Therefore, even a complicated tread pattern is advantageous for molding. These advantages are also advantageous for improving dimensional accuracy.

The rigid inner mold 2 illustrated in FIGS. 8 and 9 can also be used. The cylindrical rigid inner mold 2 is composed of segments 3 (long segment 3A, short segment 3B) divided into a plurality in the circumferential direction. Each segment 3 is configured to further divide the cylindrical circumferential surface into two in the width direction.

These segments 3 are formed in a cylindrical shape by being fixed to the peripheral portions of the opposing disk-shaped

support plates

6a and 6b via a rotation mechanism 4. That is, the segment 3 on one side obtained by dividing the cylindrical peripheral surface into two in the width direction is annularly disposed along the peripheral edge of the support plate 6a on one side of the opposing

support plates

6a and 6b. The other segment 3 that is divided into two in the width direction is annularly arranged along the peripheral edge of the other support plate 6b.

The central axis 5 is fixed so as to penetrate through the circular center positions of the opposing

support plates

6a and 6b. The center shaft 5 and the pair of

support plates

6 a and 6 b are fixed via support ribs 7 fixed to the outer peripheral surface of the center shaft 5.

In this way, the rigid inner mold 2 composed of a plurality of segments 3 formed in a cylindrical shape is configured so that each segment 3 expands and contracts with the rotation mechanism 4 as a rotation center, as will be described later. Moving. The rigid inner mold 2 is attached to the holding base of the manufacturing apparatus 1 with the central shaft 5 being pivotally supported.

In order to remove the rigid inner mold 2 from the manufactured pneumatic tire T, first, as illustrated in FIG. 10, the engagement between the respective rotation mechanisms 4 and the

support plates

6a and 6b is released. In this state, one support plate 6a is removed from the central shaft 5, and the one support plate 6a and the other support plate 6b to which the rotary shaft 5 is fixed are moved to the outside of the manufactured pneumatic tire T.

Next, as illustrated in FIG. 11, the segment 3 on one side in the width direction (upper side in FIG. 11) is rotated inside the tire so as to reduce the diameter of the rigid inner mold 2 around the rotation mechanism 4. Thereafter, the segment 3 on the other side in the width direction (the lower side in FIG. 11) is rotated inward of the tire so as to reduce the diameter of the rigid inner mold 2 around the rotation mechanism 4. In this way, the segment 3 is turned to the inside of the tire and then moved to the outside of the pneumatic tire T to be removed. In order to expand the diameter of the rigid inner mold 2 and assemble it into a cylindrical shape inside the base tire BT, a procedure reverse to the procedure of dividing the rigid inner mold 2 illustrated in FIGS. 10 and 11 may be performed. In this way, the rigid inner mold 2 can be easily disposed inside the base tire BT, and the rigid inner mold 2 can be easily taken out of the manufactured pneumatic tire T.

Studless tires can also be manufactured by using rubber compounds for studless tires as the unvulcanized rubber R. Studless tires tend to wear out in the tread portion TR as compared with ordinary pneumatic tires. However, by applying the present invention, a user can purchase a studless tire with a new tread portion TR without purchasing a new studless tire. Can be obtained. In this case, not only the rubber of the tread portion TR of the existing studless tire but also the rubber of the tread portion TR of a normal existing pneumatic tire can be used as the base tire BT. Since a new studless tire is manufactured using the base tire BT, it contributes to resource saving and energy saving. Moreover, since heat deterioration can be suppressed compared with the conventional retread technology, it can be used for a long time.

When the tire formed by cutting the rubber of the tread portion TR of the existing studless tire is used as the base tire BT, the rubber used for the tread portion TR of the existing studless tire is used as the unvulcanized rubber R. It is also possible to use a different type of rubber compound than the compound. The rubber compound of the tread part TR of the studless tire has been improved year by year, and new versions and new rubber types have been developed. Therefore, by applying the present invention, even if the user does not purchase a new studless tire having an improved rubber compound in the tread portion TR, the user can obtain a studless tire having an improved rubber compound in the tread portion TR. Obtainable. That is, the user can obtain a studless tire having the latest developed rubber compound in the tread portion TR without purchasing a new studless tire every year.

The rubber compound of the tread part TR of the studless tire is improved year by year, for example, the hardness, specific gravity and friction characteristics under the same conditions are improved. Therefore, when the tire formed by cutting the rubber of the tread portion TR of the existing studless tire is used as the base tire BT, the rubber compound and the base tire BT used in the tread portion TR of the existing studless tire are used. For example, at least one characteristic of hardness, specific gravity, and friction characteristics under the same conditions is different from that of the rubber compound of the tread portion TR formed on the outer peripheral surface. That is, these characteristics are varied to improve the performance of the studless tire. It should be noted that a plurality of or all of these characteristics may be varied.

Another embodiment of the pneumatic tire manufacturing apparatus 1 illustrated in FIGS. 12 to 13 includes a cylindrical metal rigid inner mold 2 disposed inside the base tire BT, and a base together with the rigid inner mold 2. A vulcanizing mold 10A in which a tire BT is disposed and an injection machine 13 are provided. The manufacturing apparatus 1 of this embodiment further includes cooling means 8 and 9 for cooling the rigid inner mold 2 disposed inside the vulcanizing mold 10A.

As illustrated in FIGS. 14 to 15, the rigid inner mold 2 can be divided into a plurality of parts in the circumferential direction, and a plurality of segments 3 (3A, 3B) divided in the circumferential direction are assembled in a cylindrical shape. It has a structure. Examples of the material of the rigid inner mold 2 include metals such as carbon steel, aluminum, and aluminum alloys. In this embodiment, there are two types of four long segments 3A having a relatively large circumferential length and four short segments 3B having a relatively small circumferential length. Both end surfaces in the circumferential direction of the short segment 3B are parallel in a plan view. The long segments 3A and the short segments 3B are alternately arranged in the circumferential direction.

Each

segment

3A, 3B is attached to a support arm 7a extending radially from the central axis 5. Each

segment

3A, 3B, central axis 5, and support arm 7a can be separated separately. That is, the rigid inner mold 2 is not a structure that expands and contracts, but is a structure that is separated and divided into respective segments 3 and subdivided. If necessary, the

segments

3A and 3B adjacent in the circumferential direction are connected by an appropriate connecting member on the inner peripheral side thereof.

The rigid inner mold 2 is formed by assembling the

segments

3A and 3B separated from each other into a cylindrical shape and connecting the central shaft 5 and the support arm 7a. In the formed rigid inner mold 2, the outer surfaces of the

respective segments

3A and 3B are continuously annularly contacted with the range of the tire inner surface corresponding to the tread portion TR of the base tire BT.

The vulcanizing mold 10A is composed of a plurality of divided molds 10a divided in the circumferential direction. In this embodiment, four split molds 10a are assembled in a ring shape. Each split mold 10a moves in the radial direction, the vulcanizing mold 10A is closed by moving to the radially inner peripheral side, and the vulcanizing mold 10A is moved by moving to the radially outer peripheral side. Open the mold.

The closed mold 10A for vulcanization covers the outer peripheral surface of the base tire BT corresponding to the tread portion TR of the base tire BT in which the rigid inner mold 2 is disposed. A cavity 11 is formed between the inner peripheral surface of the vulcanizing mold 10A and the outer peripheral surface of the base tire BT.

Each split mold 10 a is formed with an inner peripheral surface that forms the cavity 11 and an injection path 12 that is connected to the formed cavity 11. The inner peripheral surface of the split mold 10a forming the cavity 11 has a shape for forming a tread pattern of the pneumatic tire T to be manufactured. One end of the injection path 12 is connected to the injection port of the injection machine 13.

The other end portion of the injection path 12 is connected to, for example, the position of the inner peripheral surface of the split mold 10a corresponding to the tread land portion or the circumferential groove of the pneumatic tire T to be manufactured. The injection path 12 is preferably branched into a plurality of paths on the way and connected to the cavity 11.

Further, a heating path 14 connected to the heater 15 is formed in each split mold 10a similarly to the above-described embodiment, and the split mold 10a is similarly heated. The injection machine 13 has the same specifications as those of the above-described embodiment, and similarly injects the unvulcanized rubber R at a predetermined injection pressure. The unvulcanized rubber R has the same specifications as the above-described embodiment. The cooling means has the same specifications as those of the above-described embodiment, and the temperature of the rigid inner mold 2 (segment 3) is similarly maintained within a predetermined temperature range by the cooling means.

An example of a procedure of a method for manufacturing a pneumatic tire using the manufacturing apparatus 1 will be described.

Outside the vulcanizing mold 10A, the segment 3 is inserted inside the base tire BT and assembled into a cylindrical shape, and the rigid inner mold 2 is arranged inside. As a result, each segment 3 comes into contact with the range of the tire inner surface corresponding to the tread portion TR of the base tire BT. That is, the tire inner surface corresponding to the tread portion TR of the base tire BT is firmly supported by the segments 3 arranged in a cylindrical shape.

Next, the base tire BT is placed together with the rigid inner mold 2 in the opened vulcanization mold 10A. Next, by closing the vulcanizing mold 10A, the outer peripheral surface of the base tire BT corresponding to the tread portion TR is covered with the vulcanizing mold 10A. Thus, as illustrated in FIG. 12, a cavity 11 is formed between the inner peripheral surface of the vulcanizing mold 10A and the outer peripheral surface of the base tire BT.

Next, as illustrated in FIG. 16, unvulcanized rubber R is injected from the injector 13 into the cavity 11 and filled into the cavity 11 through the injection path 12. For example, when the base tire BT is disposed in the vulcanizing mold 10 </ b> A together with the rigid inner mold 2, the cylinder 13 a of the injection machine 13 is filled with the unvulcanized rubber R to be injected. In this way, the unvulcanized rubber R can be quickly injected into the cavity 11, so that the unvulcanized rubber R is unlikely to receive an unnecessary heat history. Accordingly, the unvulcanized rubber R can be injected in a state where the fluidity of the unvulcanized rubber R is not lowered, so that it becomes more and more advantageous to sufficiently spread the unvulcanized rubber R over the entire range of the cavity 11.

The unvulcanized rubber R filled in the cavity 11 is molded into a predetermined shape by the cavity 11. Then, the injected unvulcanized rubber R is vulcanized by the vulcanizing mold 10A heated by the heating medium flowing through the heating path.

When the unvulcanized rubber R is vulcanized, a tread portion TR made of the vulcanized rubber is formed on the outer peripheral surface of the base tire BT, and this tread portion TR is vulcanized and bonded to the outer peripheral surface of the base tire BT. And unite. Thereby, the pneumatic tire T is completed.

Next, the pneumatic tire T is taken out of the vulcanizing mold 10A together with the rigid inner mold 2 disposed inside the pneumatic tire T. Thereafter, the rigid inner mold 2 inside the pneumatic tire T outside the vulcanizing mold 10 </ b> A is separated into segments 3 and divided, and removed from the inside of the pneumatic tire T.

As described above, in the present invention, the base tire BT is supported from the inside by the solid rigid inner mold 2 in a state where the metal rigid inner mold 2 is in contact with the inner surface of the tire. Since the unvulcanized rubber R is injected into the cavity 11 in this state, it is possible to avoid the problem that the base tire BT is recessed inward due to the injection pressure of the unvulcanized rubber R.

Furthermore, the work of placing the rigid inner mold 2 inside the base tire BT and the work of removing the rigid inner mold 2 from the inside of the manufactured pneumatic tire T can be performed outside the vulcanizing mold 10A. Therefore, it is not necessary to provide the manufacturing apparatus 1 with a mechanism for performing these operations, which is advantageous for simplifying the manufacturing apparatus 1.

As the unvulcanized rubber R, a studless tire can be manufactured by using a rubber compound for a studless tire as in the embodiment described above. Moreover, what deleted the rubber | gum of the tread part TR of a normal existing pneumatic tire can also be used like the embodiment mentioned above.

The rigid inner mold 2 used in this embodiment is not a structure that expands and contracts, but is a structure that is separately separated, divided, and subdivided into segments 3. However, the structure is not limited to this embodiment, and various structures are possible. Can be adopted. For example, the rigid inner mold 2 shown in FIGS. 17 to 19 can be used.

This rigid inner mold 2 has a cylindrical shape and is composed of segments 3 divided into a plurality in the circumferential direction. Each segment 3 is configured to further divide the cylindrical circumferential surface into two in the width direction.

Connecting portions 3c are formed on the inner peripheral surfaces of the opposite ends of the segments 3 divided in the width direction. These connecting portions 3c are formed with insertion holes into which connecting members 7d such as bolts and pins are inserted. These insertion holes can be both through holes, or one can be a through hole and the other can be a hole with one end closed.

To arrange the rigid inner mold 2 inside the base tire BT, as shown in FIG. 17, the segment 3 that has been separated and divided is inserted into the base tire BT. Next, the connecting portions 3c are brought into contact with each other in a state where the outer peripheral surface of the segment 3 divided in the width direction is in contact with the inner peripheral surface of the base tire BT. Next, the connecting member 7d is inserted from one connecting portion 3c toward the other connecting portion 3c, and the segment 3 is set at a predetermined position with respect to the base tire BT. In this set state, the inner peripheral edge 3b of the segment 3 is disposed on the inner peripheral side of the bead portion Tb in contact with the bead portion Tb of the base tire BT.

Next, as illustrated in FIG. 18, a support arm 7a extending in the tire radial direction is inserted into the base tire BT, and a fitting portion 7b at the tip of the support arm 7a is connected to a connecting portion 3c in communication with a connecting member 7d. 3c. The shaft portion 7c at the rear end of the support arm 7a extends in the tire width direction, and both end portions thereof are positioned at the bead portions Tb of the base tire BT. An annular holding ring 4a that engages with the edge 3b of the segment 3 is engaged with both ends of the shaft portion 7c, and the segment 3 is fixed to the inside of the base tire BT. Each bead portion Tb of the base tire BT is sandwiched between the rigid inner mold 2 and the holding ring 4a.

Sequentially, similarly, the segment 3 is fixed so as to be adjacent to the inner side of the base tire BT in the circumferential direction, so that the cylindrical rigid inner mold 2 is arranged inside the base tire BT as illustrated in FIG. If necessary, the segments 3 adjacent to each other in the circumferential direction are connected by an appropriate connecting member on the inner peripheral side thereof. When removing the rigid inner mold 2 from the manufactured pneumatic tire T, a procedure reverse to the above-described procedure of arranging the rigid inner mold 2 inside the base tire BT may be performed. Therefore, the operation of disposing the rigid inner mold 2 inside the base tire BT and the operation of removing the rigid inner mold 2 from the inside of the manufactured pneumatic tire T can be performed outside the vulcanizing mold 10A. The rigid inner mold 2 can also be provided with the cooling path 8 described above to supply a cooling medium from the cooler 9.

Another rigid inner mold 2 illustrated in FIGS. 20 to 22 has a cylindrical shape and is composed of segments 3 divided into a plurality in the circumferential direction. The circumferential length of each segment 3 is generally shorter than the distance between the pair of bead portions Tb of the base tire BT.

In order to arrange the rigid inner mold 2 inside the base tire BT, as shown in FIGS. 20 and 21, the segment 3 is separated and divided, with the circumferential direction of the base tire BT facing the width direction of the base tire BT. Insert inside BT. Next, the circumferential direction of the segment 3 is rotated toward the circumferential direction of the base tire BT so that the outer peripheral surface of the segment 3 is in contact with the inner peripheral surface of the base tire BT. To set in place. In this set state, the inner peripheral edge 3b of the segment 3 is disposed on the inner peripheral side of the bead portion Tb in contact with the bead portion Tb of the base tire BT. An annular retaining ring 4a disposed in the vicinity of the bead portion Tb of the base tire BT is engaged with each edge portion 3b, and the segment 3 is fixed to the inside of the base tire BT. Each bead portion Tb of the base tire BT is sandwiched between the rigid inner mold 2 and the holding ring 4a.

Sequentially, similarly, the segment 3 is fixed in the circumferential direction adjacent to the inside of the base tire BT, so that the cylindrical rigid inner mold 2 is arranged inside the base tire BT as illustrated in FIG. If necessary, the segments 3 adjacent to each other in the circumferential direction are connected by an appropriate connecting member on the inner peripheral side thereof. When removing the rigid inner mold 2 from the manufactured pneumatic tire T, a procedure reverse to the above-described procedure of arranging the rigid inner mold 2 inside the base tire BT may be performed. The operation of disposing the rigid inner die 2 inside the base tire BT and the operation of removing the rigid inner die 2 from the inside of the manufactured pneumatic tire T can be performed outside the vulcanizing mold 10A. The rigid inner mold 2 can also be provided with the cooling path 8 described above to supply a cooling medium from the cooler 9.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Rigid inner type | mold 3 Segment

3A Long segment

3B Short segment

3a Auxiliary plate

3b Edge part 3c Connection part 4 Rotating mechanism 4a Holding ring 5 Center axis 5a Cylinder 6a, 6b Support plate 7 Support rib

7a Support arm

7b Fitting Part 7c Shaft part 7d Connecting member 8 Cooling path 9 Cooling machine 10 Tread mold

10A Vulcanization mold

10a Split mold 11 Cavity 12 Injection path 13 Injection machine 13a Cylinder 13b Plunger 14 Heating path 15 Heater BT Base tire T Air Enter tire Tb Bead part TR Tread part R Unvulcanized rubber

Claims

An expandable / reducible metal rigid inner mold is arranged inside the base tire, and the rigid inner mold is brought into contact with the inner surface of the tire corresponding to the tread portion of the base tire, which corresponds to the tread portion. The outer peripheral surface of the base tire is covered with a tread mold, and then the unvulcanized rubber is injected into the cavity of the tread mold to vulcanize the unvulcanized rubber. A method for manufacturing a pneumatic tire, comprising forming a tread portion on the outer peripheral surface and integrating the tread portion with the outer peripheral surface.
The rigid inner mold is constituted by a plurality of segments divided in the circumferential direction, and the segments are arranged at a diameter-expanded position so as to contact a range of the tire inner surface corresponding to the tread portion of the base tire. The manufacturing method of the pneumatic tire of description.
A cylindrical metal rigid inner mold that can be divided into a plurality of parts in the circumferential direction is arranged inside the tire, and the rigid inner mold is in contact with the inner surface of the tire corresponding to the tread portion of the tire. The base tire is placed in the vulcanization mold together with the rigid inner mold, and the outer peripheral surface of the base tire corresponding to the tread portion is covered with the vulcanization mold, and then the vulcanization is performed. The unvulcanized rubber is injected into a cavity formed between the inner peripheral surface of the mold for use and the outer peripheral surface of the base tire, and this unvulcanized rubber is vulcanized to form the outer peripheral surface of the base tire. A pneumatic tire is manufactured by forming a tread portion and integrating the tread portion with the outer peripheral surface. The pneumatic tire is vulcanized together with the rigid inner mold disposed inside the pneumatic tire. Take out from the mold for vulcanization The pneumatic tire manufacturing method which is characterized in that the outer mold removing the rigid inner die from the inside of the pneumatic tire.
4. The cylinder according to claim 3, wherein when the base tire is placed in the vulcanizing mold together with the rigid inner mold, the unvulcanized rubber to be injected is filled into a cylinder in which a plunger of an injection machine is installed. A method of manufacturing a pneumatic tire.
The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein the unvulcanized rubber is injected and vulcanized while cooling the inside of the base tire through the rigid inner mold.
The method for manufacturing a pneumatic tire according to any one of claims 1 to 5, wherein the base tire is formed by cutting rubber in a tread portion of an existing pneumatic tire.
The method for manufacturing a pneumatic tire according to any one of claims 1 to 6, wherein a studless tire is manufactured using a rubber compound for a studless tire as the unvulcanized rubber.
The existing pneumatic tire is a studless tire, and a rubber compound of a type different from a rubber compound used for a tread portion of the existing studless tire is used as the unvulcanized rubber. The manufacturing method of the pneumatic tire of Claim 7.
The rubber compound used in the tread portion of the existing studless tire and the rubber compound of the tread portion formed on the outer peripheral surface of the base tire have at least one characteristic of hardness, specific gravity, and friction characteristics under the same conditions. The manufacturing method of the pneumatic tire according to claim 8 which is different.
A metal inner rigid mold that can be expanded and contracted disposed inside the base tire, a tread mold that covers the outer peripheral surface of the base tire corresponding to the tread portion, and a cavity of the tread mold An injection machine for injecting unvulcanized rubber, and configured to inject the unvulcanized rubber in a state in which the rigid inner mold is in contact with the inner surface of the tire corresponding to the tread portion of the base tire. A pneumatic tire manufacturing apparatus.
The pneumatic tire manufacturing apparatus according to claim 10, wherein the rigid inner mold is configured by a plurality of segments divided in a circumferential direction.
A cylindrical metallic rigid inner mold that can be divided into a plurality of circumferentially arranged parts inside the base tire, and the base tire corresponding to the tread portion, wherein the base tire is disposed inside together with the rigid inner mold A vulcanizing mold that covers the outer peripheral surface, and an injection machine that injects unvulcanized rubber into a cavity formed between the inner peripheral surface of the vulcanizing mold and the outer peripheral surface of the base tire, The unvulcanized rubber is vulcanized by injecting the unvulcanized rubber into the cavity with the rigid inner mold in contact with the inner surface of the tire corresponding to the tread portion of the base tire. After the formed tread portion is integrated with the outer peripheral surface of the base tire to manufacture a pneumatic tire, the rigid inner mold disposed inside the pneumatic tire is combined with the manufactured pneumatic tire and the added tire. Removed from the mold The vulcanizing mold manufacturing apparatus of a pneumatic tire is characterized in that the structure to be removed from the inside of the pneumatic tire in outside.
The pneumatic tire manufacturing apparatus according to any one of claims 10 to 12, further comprising cooling means for cooling the rigid inner mold.